Kapillar

Kapillar is a term used in several languages, closely related to the English word capillary. It denotes capillaries or capillary-related phenomena, spanning anatomy, physics, and engineering.

In anatomy, capillaries are the smallest blood vessels that connect arterioles and venules and form the microcirculation. Their walls consist of a single layer of endothelial cells with a thin basement membrane, enabling rapid exchange of gases, nutrients, and waste between blood and surrounding tissue. Capillary density and structure vary by tissue, with major types including continuous, fenestrated, and sinusoidal capillaries, each adapted to specific physiological needs.

In physics and chemistry, capillarity (kapillarity) describes the spontaneous movement of liquids in narrow spaces due to cohesion and adhesion. The phenomenon can be quantified by relationships such as Jurin’s law, which relates capillary rise height to surface tension, contact angle, liquid density, gravity, and tube radius. Capillary action is important in natural processes—such as water transport in soils and plant xylem—and in engineered systems involving narrow channels and porous materials.

In technology and medicine, capillary tubes and membranes are used in chromatography, microfluidics, blood analysis, and filtration. Capillary electrophoresis and capillary chromatography rely on small-diameter tubes to separate substances under electric fields or flow. Etymology traces back to Latin capillus, meaning hair, reflecting the slender, hair-like nature of capillaries; the term appears in various languages with related forms, including Kapillar in German.

Overall, Kapillar encompasses the structure and phenomena of capillaries across biological and technological contexts.